The connection of a.c. power controllers with the wiring of buildings, and for similar purposes, is frequently obtainable only with one side of the a.c. power line. For example, the looping of a wall switch circuit from a ceiling light or the like is very often done with a two-conductor "Romex" cable: e.g., only the "black" (hot) side of the a.c. circuit is interrupted somewhere between the a.c. source and the light fixture. Full line power is therefore not actually brought to the wall switch location. The whole arrangement takes on the schematic equivalence of a series circuit.
As a result of this common style of wiring practice, it is necessary that any electrical device intended to find popular acceptance as a replacement for, or supplement to, the function of the ubiquitous wall switch must rely upon merely the power present in the one side of the circuit. Such a device must be series circuit connectable, depending solely upon current flow through one side of the circuit as the primary source of any operating potentials.
In my earlier U.S. Pat. No. 4,300,090 I provided a "Direct Current Power Supply" operable from merely one side of an a.c. power circuit. Operation was obtained from the current flow through a thyristor, which was further devised to have its turn-ON during at least on one-half of each a.c. power cycle slightly retarded, whereby the small pre-conduction potential which then developed across the thyristor was rectified and utilized as a source of low-voltage direct current having good stability with few parts.
In my subsequent U.S. Pat. No. 4,336,464 I addressed the operation of a "Two Terminal Timed Electric Switch" which adapted my earlier power supply patent to that of satisfying the need for an a.c. timed wall switch or the like which obtains all of its operating potentials from merely one side of the a.c. line.
I have now recognized that further improvement can be obtained by providing apparatus which, together with the method for operating that apparatus, obtains full ON and OFF operation of the a.c. power line and produces a low-voltage source of direct current power from but one side of the a.c. line. I also now reveal how such operation may be obtained using few and inexpensive parts in a non-critical hookup arrangement which lends itself to low cost mass production.
The capability for coming forth with a relatively stable source of low voltage d.c. power from the series a.c. power circuit hookups taugt in my earlier -090 patent does not provide any obvious arrangement for turning the a.c. power flow ON and OFF, aside from that of a separate mechanical switch or the like.
The turning ON and OFF of the a.c. power flow by the circuit taught in my -464 patent is also silent regarding the obtaining of necessitous switching action integral with the d.c. power supply portion of the circuit: e.g., as separate switch and power supply control thyristor device is shown.
In view of my earlier art forms, I realized that it would be advantageous in both the sense of circuit economy, as well as mere eloquence, to obtain ON and OFF switching of the a.c. power with subsantially the same parts of a device's circuitry which produces the d.c. power for its operation. Aside from being cheaper and simpler to build, fewer parts also may mean less potential for premature failure. Some savings in size, and less power dissipation also benefits from such functional consolidation.